Grinding fixture



Dec. 27,r 193s. P. E, LEHMAN 2,141,187

GRINDING FIXTURE Filed NOV. 8,'1935 2 Sheets-Sheet 1 d IVENTQR y v l l v mrromr De.27,193s. RELEHMAN y I 2,141,187

` GRIND'ING FIXTURE Filed Nov. 8, 1935 1 2 Sheets-Sheet 2 y I INVENTOR @Ef-M ATTORNEY l Patented Dec. 27, 1938 UNITED STATES PATENT OFFICE 6 Claims.

My invention relates to grinding fixtures and particularly to adjustable grinding fixtures for adjustably supporting tools or cutters during the grinding or sharpening thereof.

6 It is an object of my invention to provide an improved adjustable grinding fixture capable of supporting different types of tools or cutters and adapted for use with any type of grinding machine, such as surface grinders, tool grinders, or

10 a common machine with a movable table combined with an electric tool grinder.

It is a further object of my invention to provide a grinding fixture wherein the cutter or tool to x be sharpened is rotatably mounted on a cutter supporting means carried by av cutter carrying member, which member is itself rotatable through an arc of 360 on an axis at right angles to the axis of the cutter supporting means.

In is a m11 further object of my invention 1n pivotally mount the cutter carrying member on an intermediate member pivotally mountedl on a fixed base whereby the cutter or tool to be sharpened may be inclined at substantially any required angle during the process of sharpeningor grinding thereof.

Still further objects of my invention include the provision of an indexing device carried by the tool carrying member and adjustably mounted for movement into and out of contact with the cutter to be ground; to provide certain ground surfaces on the fixture whereby a protractor or the like may be used for determining the proper angle at which thecutter is to be set; to provide an improved locking device whereby the various movable elements of the xture may be locked in the desired position without affecting a change in such position during the locking operation; and to provide other specific improvements which will become apparent from a brief consideration of the xture itself, a specific embodiment of which I have describedin the following specification, taken in conjunction with the drawings forming a part hereof.

In the drawings: Fig. 1 is a front elevation of my improved xture;

Fig. 2 is a side elevation thereof; and Fig. 3 is a view in elevation showing the three main parts of the device separated. My improved fixture, as shown on the drawings illustrating one form thereof, consists `primarily of three elements, namely a base member I0, an intermediate member II, and a tool carryp ing member I2. The intermediate member II is pivotally mounted on the base II) for oscillatory movement at right angles to the longitudinal axis of the base II). The tool carrying member I 2 is pivotally mounted on the intermediate member I I for oscillatory movement in planes parallel to the longitudinal axis of the base. Thus, with 5 respect to the base member IIl, the tool carrying member I2 is movable in a plane at right angles to the longitudinal axis of the base and is rotatable through an arc of 360 degrees in a plurality of planes parallel to the longitudinal axis 10 of the base. This movement of the tool carrying member through an arc of 360 degrees permits the grinding or sharpening of any type of milling machine cutter and particularly diiiicult angle cutters, by use of flat grinding surfaces. l5

An important feature of my invention is the means for mounting the member I2 on the intermediate member II and for mounting the intermediate member I I on the base I IJ, and the means in conjunction therewith for locking these ele- 20 ments in the desired positions. To this end, intermediate member II includes a bifurcation consisting of the two leg portions I4 and I 5 straddling the lug I3 formed in the base member I0. A ground tube or hollow shaft I extends through 25 the openings I8 in the leg portions I4 and I5 and passage I9 in the lug I3. This shaft I6 constitutes a bearing on which the intermediate member I I oscillates with respect to the base member IIJ, and insures an accurate movement of the in- 30 termediate member with respect to the base member II. This tube or hollow shaft ts snugly in the openings I 8 and considerable force is required Vto remove it therefrom. There is sufficient frictional resistance between the tube I6 and the in- 35 termediate member II that a slight force is required to move the member I I with respect to the base member II). This frictional resistance maintains the member I I in position with relation to thebase Ill during the locking operation. 40

To lock the member I I in position with respect `to the base I0, I have provided a bolt I'I extending the base IU, during the locking or unlocking oper- 50 ation.

Substantially the same construction is used for the pivotal mounting of the cutter carrying member I2v on the intermediate member II and for locking these members in assembled positions. 55

For example, the leg portions I4 and I5 of the intermediate member I I extend upwardly and join to form lugs 2l and 22 each provided with holes 23. The cutter carrying member I2 fits between the lugs V2l and 22 and is supported for oscillatory movement in such position by means of a hollow shaft 2l passing through openings 23 and through the passage 25 formed in the member I2. This hollow shaft correponds to the hollow shaft it previously referred to and constitutes a bearing for the tool holding member I2 and insures the precision movement of member I2 relative to the intermediate member I I. It fits snugly in the openings 23 and considerable force is required to remove it therefrom. There is sufficient frictional resistance between the tube 2l and the member I2 that a slight force is required to move member I2 relative to the tube 21. This frictional resistance maintains the element I2 in its selected position during 'the locking operation.

A bolt 263 passes through the hollow shaft 2'I and together with the nut 26, serves to lock the member I2 in position with respect to the intermediate member Ii.- This bolt 20. fits loosely in the tube 2'! and serves merely to lock members Il and I2 in position. It may be tightened or loosened without affecting the setting of the members Ii and I2.

If desired the hollow shafts I6 and 21 may be sealed and protected from possible damage resulting from small particles of metal, grit or grinding material falling thereon by means of grease packed into and retained by the grooves 3l.

The tool carrying member l2 comprises the central body portion 28 and leg portions 29 and 3Q extending laterally from the body portion 23 and at right angles to each other. Each leg portion includes a means for supporting a tool, such as a cutter, to be ground or sharpened. This means comprises the ring guide member 3i integral with the leg portion 29 and surrounding a shaft 35 pressed or threaded into or even integral with leg portion 2B and having a passage 36 therein.

In the particular embodiment shown, the cutter 39, iits over the shaft 35, is rotatable thereon,

and slidably engages the ring member 34, being heldin position by means of a C washer 38 tting over the bolt 8 having a head EI larger than the slot fil of the C washer. 'I'he bolt Ill passes through the passage 32 and on the other side of the leg portion 29 the bolt le is surrounded by a spring i3 having one end bearing against the leg portion 2% and its other end bearing against a washer retained by the nut i5 threaded on the bolt fit. When in position on the tool c-arrying member i2, the cutter 39 rotates about the shaft 35.

An important feature of my invention is the location of the axis about which the tool carrying member l2 rotates with respect to the intermediate member il. As shown on the drawings, this axis, comprising the tube or hollow shaft 21, is located within the body portion 28 of the member I2 and substantially at the center thereof. This'arrangement, in addition to providing a low center of gravity, also permits the rotation of the member I2 through an arc of 360 degrees, whereby the member i2 may be set at any required angle.

During the grinding or-sharpening operation, it is desirable to limit the rotation ofthe cutter itself to one direction. It is also desirable to provide means for indexing or holding each tooth of the cutter in position to be ground or sharpened. Both of these functions are performed by the leaf spring member 50 carried by the member I2 and movable therewith and adapted to engage to straight sides of the teeth to thereby act as a pawl for preventing counter-clockwise movement of the cutter and at the same time indexing each tooth to a grinding position.

This spring 56 is carried by the arm 5| removably mounted in the clamping lugs 53 through which passes the bolt 54. These lugs 53 form part of the arm 56 removably mounted on the extension 55 forming a part of the tool carrying member I2. This arrangement permits the spring 50 to be moved into and out of engagement with the cutter 39. When in position it permits rotation of the cutter in a clockwise direction due to its resiliency but prevents movement in counter-clockwise direction. As previously pointed out it likewise indexes each tooth of the cutter to a proper position for grinding.

Only the one cutter supporting means, namely that formed on the lug portion 29, has been specifically described. However, a similar means indicated generally at B is provided, differing merely in its size for it is constructed to receive and support a cutter or tool of different size center depression.

I have also provided means whereby the proper setting of the tool holding member I2 with respect to the base Iil may easily be determined. In the particular embodiment shown, the upper surface 'I0 of the base member Ill is ground to present a perfectly level surface. The surface l! of the leg portion 2S and a corresponding surface on the leg portion 3B are also ground level. By placing a protractor upon the surface l0, the member I2 can be rotated and adjusted to the desired angle without difculty. Likewise the intermediate member II may similarly be moved and adjusted to the proper angle.

From the above brief description of my improved adjustable cutter fixture, it will be apparent that I have provided a fixture wherein a full universal movement of the cutter is obtained, and wherein full rotary movement of the cutter carrying member I2 on its tubular axis 21 is possible.l This full rotary movement provides a means whereby the cutter to be ground or sharpened may be set at any desired angle. It will also be apparent that by reason of the improved type of mounting, I can obtain very accurate movement of the movable elements with respect to one another without possibility of disturbing the accurate setting of the members during the locking or unlocking operation.

While I have described one form of my invention, other modifications coming within the scope of the appended claims, are clearly Within the scope of my invention.

Vhat I claim as new is:

l. A fixture comprising a base member, a tool carrying member and Ymeans for pivotally mounting said tool carrying member on said base, said means including a removable tubular member extending through said base member and said carrying member and a means for locking said members in the desired relative position, said locking means including a threaded bolt extending loosely through said tubular member.

2. A fixture comprising a base, a member pivotally mounted on said base, said member comprising two leg portions extending laterally of the pivotal mounting and at rightl angles to each other, Vmeans on each of said leg portions for rotatably supporting a tool to be sharpened or ground and means carried by said member and movable into engagement with either of said tools for preventing rotational movement thereof in one direction.

3. A portable tool grinding fixture comprising a base, a member pivoted to said base and including a pair of spaced apart supporting lugs, a cutter supporting means pivotally mounted on said member and between said lugs and mounted for full rotary movement about an axis at right angles to the axis about which said member pivots, said cutter supporting means including two leg portions extending laterally on opposite sides of said pivoted mounting and at right angles to each other and means on each of said leg portions for supporting a cutter to be ground.

4. A portable tool grinding xture comprising a base, a member pivoted to said base, a cutter supporting means pivotally mounted on said member and mounted for full rotary movement about an axis at right angles to the axis about which said member pivots, said cutter supporting means including two leg portions extending laterally on opposite sides of said pivoted mounting and at right angles to each other, means on each of said leg portions for supporting a cutter to be ground and indexing means carried by said cutter supporting means and movable into contact with either of said cutters.

5. A device of the class described including a base member, an intermediate member pivoted thereto about an axis, means for limiting the movement of said intermediate member through an arc of less than 360, said intermediate member including a pair of spaced apart supporting lugs, a tool carrying member supported on said intermediate member between said lugs and mounted for full rotary movement through an arc of 360 on an axis extending through said lugs, said last named axis being substantially at right angles to the rst mentioned axis and said axes lying in substantially parallel planes.

6. A device of the class described including a base member, an intermediate member pivoted thereto rabout an axis, means for limiting the movement of said intermediate member through an arc of less than 360, said intermediate member including a pair of spaced apart supporting lugs, a toolcarrying member carried by said intermediate member between said lugs and mounted for full rotary movement through an arc of 360 on an axis extending through said lugs, said last named axis being substantially at right angles to the iirst mentioned axis and said axes lying in substantially parallel planes, said tool carrying member including a central body portion and two leg portions extending laterally and at right angles to each other on either side of said central body portion. v

. PAUL E. LEHMAN. 

